"Our supplier has failed us and in turn we have failed you," Burger King vice president for global quality Diego Beamonte told The Guardian. He said that Burger King is "deeply troubled" by the findings.

The company also said that burgers tested from its restaurants showed no trace of horse meat.

Here's the statement from Burger King — from The Guardian:

"Our independent DNA test results on product taken from restaurants were negative for any equine DNA. However, four samples recently taken from the Silvercrest plant have shown the presence of very small trace levels of equine DNA. Within the last 36 hours, we have established that Silvercrest used a small percentage of beef imported from a non-approved supplier in Poland. They promised to deliver 100% British and Irish beef patties and have not done so. This is a clear violation of our specifications, and we have terminated our relationship with them."

The fast food chain had previously given "absolute assurances" that its burgers weren't involved, The Daily Mail reported.

The culprit is suspected to be a meat distributor in Poland, which may have used other meats as filler.